The invention relates to devices which are used for testing internal combustion engines. The primary functions which are capable of being executed by the device of the invention are to operate as a timing light, as a tachometer, as a cam dwell angle meter and as a voltmeter.
The primary quality of the invention is its simplicity and its totally foolproof character.
Multiple function testing devices for internal combustion engines have been in use for a number of years. One such device which has enjoyed great success is shown and described in U.S. Pat. No. 3,693,073, and is assigned to the same assignee as this application. The device described in the aforementioned patent operated as a timing light, as a tachometer and as a cam dwell angle meter. In order to operate as a tachometer or as a cam dwell angle meter a test lead was connected to the distributor of the engine. In order to operate as a timing light, the test lead was connected to the positive terminal of the engine battery. A switch then selectively connected the test lead to the appropriate one of the timing light circuitry, tachometer circuitry and cam dwell angle, measuring circuitry in order to perform the necessary testing.
In many instances it is desirable to be able to test and adjust the timing of an internal combustion engine while simultaneously testing and adjusting either the dwell or engine R.P.M. It is additionally desirable to be able to test voltage at various points in the engine in order to locate various problems which can be present in the engine. It is particularly important to be able to check battery voltage during engine operation in order to check proper operation of the engine regulator and generator. Of course, if these checks are made, they should be made at particular settings of engine R.P.M. because of the instrumentationship between R.P.M. and generator and regulator voltage.
Previous devices, including the device referenced in the above noted patent, required switching test leads between at least two engine points in order to perform certain ones of the functions which could be performed. No devices known are capable of simultaneously performing at least two of the functions in order to simultaneously perform a number of engine tests which are best performed simultaneously. Although a number of devices may be attached to an engine in order to perform all functions simultaneously, useage of a number of devices simultaneously is cumbersome and expensive, and in many cases quite difficult because of the number of adjustments which must be made to each of the devices employed.